Routers may generally be defined as hand-held power driven tools, in which a router bit is rotated rapidly against a work piece. Various different bits are provided for producing different formations in a work piece such as wood, plastic materials, or softer metals.
Routers are widely available in a range of sizes and horsepowers. Routers at the low end of this range are usually used for edge trimming of materials such as laminates. These laminates may include veneers, plastic laminates, light gauge metals and the like. Such laminates may be applied to a base material to provide a desired surface effect. For example, plastic laminates such as "Arborite" (trade mark) and similar laminate materials are used as surfaces on items such as counter tops, table tops, doors, walls, and the like, both in the home and in numerous commercial institutions such as retail stores, banks, and the like.
In the great majority of cases, these laminates are applied on a custom-made basis. In many cases, especially in commercial institutions, relatively complex formations or grooves or recesses may be formed in these counter tops, or other surfaces, and the laminate is required to be applied to the interior surfaces of these recesses. In almost all cases, the laminate is applied with a substantial overlap, extending over the edge of the base material. Adhesive is used to apply to laminate, and when the adhesive is cured, the excess edge portions of the laminate are trimmed away. This is customarily done with a small hand-held router, known in the trade as an edge trimmer.
This tool has a capacity to accept router bits of varying diameters, for various different jobs. In order to guide these routers or edge trimmers, along the edge of a work piece, a crude form of roller device has been provided which, in some cases, clamped on the side of the router, and in others on the bit itself. This roller was intended to ride along the side edge of the work piece, so as to ensure a uniform cut with the router bit along the edge. In practice, however, the design of the roller guide was such that they could not enter into corners, or small recesses. In these areas, the guide must simply be removed and the router controlled by hand alone. This is, in fact, virtually impossible, and the usual practice is to use a hand file instead.
The router bit rotates at up to 30,000 r.p.m. An operator cannot control the direction of a hand-held router at these speeds. Consequently, the laminate may be damaged. If this happens the entire job must be reworked. This means cutting a new base, applying a new laminate surface, and again retrimming the edge. Further problems arise due to the complexities of the design of the counter top or other base. It is usually required to apply a laminate both to the top surface and to the edge surfaces. This is also true when grooves or recesses are formed in the counter top. Laminates must be applied to the exposed surfaces of the recess. Where an edge surface meets a top surface, the procedure is to apply one part of the laminate, i.e., either the top surface or the edge surface first, trim it back, and then apply the other portion of the laminate, to the other surface and then trim it back.
The end result, which it is intended and desired to achieve, is a corner junction between, for example, the top surface laminate and the edge laminate, which is perfectly joined, and trimmed. In some cases, it is desirable to provide a bevel surface on the edge, either of the top surface laminate or the edge laminate, which overlaps the other laminate. This process is particularly difficult to achieve. It means that the first laminate surface to be applied must be trimmed square and exactly flush with the edge of the base material. The second laminate must then be applied, overlapping the trimmed edge of the first laminate. The edge of the second laminate must then be trimmed along a bevel angle, so as to overlap the edge of the first laminate. Using the relatively crude roller guide system presently available, this task is simply impossible. In practice, when a workman is asked to perform this task, he does not use the router or edge trimmer at all. Instead he simply works with a hand file. This is highly skilled work, and must be done slowly and carefully, and seldom, if ever, produces a perfect result.
In order to overcome some of these problems, routers have been developed in which the bit is set at a predetermined angle to the base plate. These so called "bevel" routers were also difficult to control by hand, and were subject to the disadvantages noted above, and explained in more detail below.
In some cases, it is necessary to use such a router or edge trimmer in confined spaces such as, for example, around the edges of an inside opening. For example, it may be required to apply a laminate over a door, or over a metal plate, having a series of recesses or openings, e.g., hinge recesses, lock openings, or openings for push buttons. The laminate must be trimmed around the edge of each of the recesses or openings. Preferably, in order to trim the edges around such openings, all that would be required would be to simply apply a layer of laminate over the entire panel, covering the openings. Holes would then simply be drilled through the laminate registering with each of the openings. The router bit would then be inserted through the drilled holes, and the edges trimmed. In practice, however, using existing routers and guides, this is impossible. This type of work must simply be done by laborious hand filing.